Polarization Charges in a High-Performance GaN/InGaN Core/Shell Multiple Quantum Well Nanowire for Solar Energy Harvesting

The influence of polarization charges on the performance of III-nitride multiple quantum well (MQW) based nanowire photovoltaic devices due to stress and strain at heterointerfaces is investigated. The 7 x GaN/InxGa1-x N core/shell MQW triangular nanowire solar cell with {0001}, {1 (1) over bar 0 (1) over bar}, {(1) over bar 10 (1) over bar} or {000 (1) over bar}, {1 (1) over bar 01}, {(1) over bar 101} set of facets is intensively studied by numerical calculations. It is observed that the behavior of QWs in different facets of nanowire solar cells possesses an irregular pattern due to a complex distribution of strain and stress parameters depending on crystallographic orientations. Finally, the effect of polarization charges on optical and electrical performance of the nanowire solar cell is investigated in detail. It reveals that QWs along {000 (1) over bar} facet of the nanowire have a favorable influence on III-nitride nanowire photovoltaic devices. It is interesting to observe that a remarkable efficiency of similar to 9.82% with 94.34% fill factor and more than 70% quantum efficiency is achieved from 7 x GaN/In0.1Ga0.9N MQWs sandwiched between n-GaN and p-GaN layer under 1 Sun AM1.5 illuminations.